This is the HPI Roto Start 2 Electric Shaft Drive Starter System for the HPI Nitro Star K series engines with a pull starter. FEATURES: Replaces pull starter with a durable metal gear backplate Upgraded version of the original Rotostart with an improved case with shaft storage holder and a circuit breaker for overload protection Thumb-start button has safety cover to prevent accidental starting INCLUDES: HPI Roto Start 2 Electric Shaft Drive Start with shaft, metal gear backplate with mounting hardware, 2mm hex wrench, Z164 heavy duty grease and illustrated instruction manual REQUIRES: 7.2V rechargeable stick battery pack (DTXC2010) and charger (DTXP4190) SPECS: Rotor Start 2 Shaft Length: 7.9" (201mm) Length: 7.2" (182mm) Width: 2" (51mm) Diameter: 0.20" (5.5mm) Height: 3.9" (100mm) COMMENTS: Other Roto Start 2 Systems include; HPIP7130 for HPI Nitro Star F series engines HPIP7132 for HPI Nitro Star .12/.15/.18 size engines jxs 6/07/06 ir/jxs